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close this bookEnvironmental Handbook Volume II: Agriculture, Mining/Energy, Trade/Industry (GTZ/BMZ, 1995, 736 pages)
close this folderMining and energy
close this folder36. Surface mining
View the document1. Scope
View the document2. Environmental impacts and protective measures
View the document3. Notes on the analysis and evaluation of environmental impacts
View the document4. Interaction with other sectors
View the document5. Summary assessment of environmental relevance
View the document6. References

1. Scope

Surface mining is the term used to describe diverse forms of raw-material extraction from near-surface deposits. It involves the complete removal of nonbearing surface strata (overburden) in order to gain access to the resource. Depending on the physical characteristics of the raw material and on the site-specific situation, various surface-mining techniques are applied:

Dry extraction of loose or solid raw materials: In hardrock mining, the product must first be "worked" (loosened). Then, it can be loaded, hauled and processed by mechanical means similar to those employed in loose-rock mining. Accordingly, dry surface mines require appropriate dewatering.

In wet-extraction, or dredging, operations, loose raw materials are mechanically or hydraulically extracted and transferred to a processing facility. The entire extraction equipment is normally located on/in the water, often floating on a river or artificial lake.

Offshore, or shelf, mining is the term used to describe the extraction of loose material from nearshore deposits (marine beach placers). Like in wet extraction, the material is excavated and conveyed by mechanical or hydraulic means.

Deep sea mining is a - future - form of mining in which raw materials are extracted from ocean beds; not to be dealt with in the present context.

The various surface mining techniques are applied to different types of raw material reservoirs.

Table 1 - Forms of surface mining and major raw-material products

Hardrock mining Loose-rock mining  
dry extraction dry extraction wet extraction
        terrestrial offshore
building stones
diamonds
gems
feldspar
gypsum
limestone/
raw materials for cement
metalliferous ores (copper, iron, silver, tin)
oil shale
hard coal
uranium ore
brown coal
diamonds
gold
kaolin/
china clay
phosphates
sand, gravel
heavy minerals (ilmenite, rutile, RE-minerals1), zircon)
clay
tin ore
diamonds
gold
heavy minerals
tin ore
sand, gravel
diamonds
heavy minerals (ilmenite, rutile, zircon, monazite)
tin ore

1) RE-minerals = rare-earth minerals

Surface mines vary in size according to the nature of the deposit and the employed techniques of extraction. Among terrestrial workings, one encounters mines ranging in size from small one-man operations to huge strip mines measuring several kilometers in diameter. Due to the elaborate, expensive technology required, marine workings always strive toward minimum dimensions.

Since mining amounts to a site-bound activity, new and expanding operations often have to compete with other potential users of the premises in question, and the infrastructure required for surface mining operations may still have to be established. As regards the demarcation of surface mining activities, it is inherently difficult to separate them from the required mineral dressing facilities, because such processing normally takes place directly at the place of extraction.